451 lines
14 KiB
Python
Executable File
451 lines
14 KiB
Python
Executable File
#!/usr/bin/env python
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# source: https://github.com/nbering/terraform-inventory
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'''
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Terraform Inventory Script
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==========================
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This inventory script generates dynamic inventory by reading Terraform state
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contents. Servers and groups a defined inside the Terraform state using special
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resources defined by the Terraform Provider for Ansible.
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Configuration
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=============
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State is fetched using the "terraform state pull" subcommand. The behaviour of
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this action can be configured using some environment variables.
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Environment Variables:
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......................
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ANSIBLE_TF_BIN
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Override the path to the Terraform command executable. This is useful if
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you have multiple copies or versions installed and need to specify a
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specific binary. The inventory script runs the `terraform state pull`
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command to fetch the Terraform state, so that remote state will be
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fetched seemlessly regardless of the backend configuration.
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ANSIBLE_TF_DIR
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Set the working directory for the `terraform` command when the scripts
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shells out to it. This is useful if you keep your terraform and ansible
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configuration in separate directories. Defaults to using the current
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working directory.
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ANSIBLE_TF_WS_NAME
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Sets the workspace for the `terraform` command when the scripts shells
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out to it, defaults to `default` workspace - if you don't use workspaces
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this is the one you'll be using.
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'''
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import sys
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import json
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import os
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import re
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import traceback
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from subprocess import Popen, PIPE
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TERRAFORM_DIR = os.environ.get('ANSIBLE_TF_DIR', os.getcwd())
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TERRAFORM_ENV = os.path.join(TERRAFORM_DIR, '.terraform/environment')
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TERRAFORM_PATH = os.environ.get('ANSIBLE_TF_BIN', 'terraform')
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TERRAFORM_BPK = os.path.join(TERRAFORM_DIR, '.terraform/terraform.tfstate.backup')
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def _tf_env():
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# way to figure out currenly used TF workspace
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try:
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with open(TERRAFORM_ENV) as f:
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return f.read()
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except:
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return 'default'
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TERRAFORM_WS_NAME = os.environ.get('ANSIBLE_TF_WS_NAME', _tf_env())
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ANSIBLE_BKP = os.path.join(TERRAFORM_DIR, 'ansible/inventory', _tf_env())
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class TerraformState(object):
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'''
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TerraformState wraps the state content to provide some helpers for iterating
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over resources.
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'''
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def __init__(self, state_json):
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self.state_json = state_json
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if "modules" in state_json:
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# uses pre-0.12
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self.flat_attrs = True
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else:
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# state format for 0.12+
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self.flat_attrs = False
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def resources(self):
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'''Generator method to iterate over resources in the state file.'''
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if self.flat_attrs:
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modules = self.state_json["modules"]
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for module in modules:
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for resource in module["resources"].values():
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yield TerraformResource(resource, flat_attrs=True)
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else:
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resources = self.state_json["resources"]
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for resource in resources:
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for instance in resource["instances"]:
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yield TerraformResource(instance, resource_type=resource["type"])
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class TerraformResource(object):
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'''
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TerraformResource wraps individual resource content and provide some helper
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methods for reading older-style dictionary and list values from attributes
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defined as a single-level map.
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'''
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DEFAULT_PRIORITIES = {
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'ansible_host': 50,
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'ansible_group': 50,
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'ansible_host_var': 60,
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'ansible_group_var': 60
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}
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def __init__(self, source_json, flat_attrs=False, resource_type=None):
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self.flat_attrs = flat_attrs
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self._type = resource_type
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self._priority = None
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self.source_json = source_json
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def is_ansible(self):
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'''Check if the resource is provided by the ansible provider.'''
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return self.type().startswith("ansible_")
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def priority(self):
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'''Get the merge priority of the resource.'''
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if self._priority is not None:
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return self._priority
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priority = 0
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if self.read_int_attr("variable_priority") is not None:
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priority = self.read_int_attr("variable_priority")
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elif self.type() in TerraformResource.DEFAULT_PRIORITIES:
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priority = TerraformResource.DEFAULT_PRIORITIES[self.type()]
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self._priority = priority
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return self._priority
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def type(self):
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'''Returns the Terraform resource type identifier.'''
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if self._type:
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return self._type
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return self.source_json["type"]
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def read_dict_attr(self, key):
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'''
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Read a dictionary attribute from the resource, handling old-style
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Terraform state where maps are stored as multiple keys in the resource's
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attributes.
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'''
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attrs = self._raw_attributes()
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if self.flat_attrs:
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out = {}
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for k in attrs.keys():
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match = re.match(r"^" + key + r"\.(.*)", k)
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if not match or match.group(1) == "%":
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continue
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out[match.group(1)] = attrs[k]
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return out
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return attrs.get(key, {})
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def read_list_attr(self, key):
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'''
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Read a list attribute from the resource, handling old-style Terraform
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state where lists are stored as multiple keys in the resource's
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attributes.
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'''
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attrs = self._raw_attributes()
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if self.flat_attrs:
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out = []
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length_key = key + ".#"
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if length_key not in attrs.keys():
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return []
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length = int(attrs[length_key])
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if length < 1:
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return []
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for i in range(0, length):
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out.append(attrs["{}.{}".format(key, i)])
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return out
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return attrs.get(key, None)
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def read_int_attr(self, key):
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'''
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Read an attribute from state an convert it to type Int.
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'''
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val = self.read_attr(key)
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if val is not None:
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val = int(val)
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return val
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def read_attr(self, key):
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'''
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Read an attribute from the underlaying state content.
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'''
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return self._raw_attributes().get(key, None)
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def _raw_attributes(self):
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if self.flat_attrs:
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return self.source_json["primary"]["attributes"]
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return self.source_json["attributes"]
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class AnsibleInventory(object):
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'''
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AnsibleInventory handles conversion from Terraform resource content to
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Ansible inventory entities, and building of the final inventory json.
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'''
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def __init__(self):
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self.groups = {}
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self.hosts = {}
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self.inner_json = {}
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def add_host_resource(self, resource):
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'''Upsert type action for host resources.'''
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hostname = resource.read_attr("inventory_hostname")
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if hostname in self.hosts:
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host = self.hosts[hostname]
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host.add_source(resource)
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else:
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host = AnsibleHost(hostname, source=resource)
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self.hosts[hostname] = host
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def add_group_resource(self, resource):
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'''Upsert type action for group resources.'''
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groupname = resource.read_attr("inventory_group_name")
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if groupname in self.groups:
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group = self.groups[groupname]
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group.add_source(resource)
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else:
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group = AnsibleGroup(groupname, source=resource)
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self.groups[groupname] = group
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def update_groups(self, groupname, children=None, hosts=None, group_vars=None):
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'''Upsert type action for group resources'''
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if groupname in self.groups:
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group = self.groups[groupname]
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group.update(children=children, hosts=hosts, group_vars=group_vars)
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else:
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group = AnsibleGroup(groupname)
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group.update(children, hosts, group_vars)
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self.groups[groupname] = group
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def add_resource(self, resource):
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'''
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Process a Terraform resource, passing to the correct handler function
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by type.
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'''
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if resource.type().startswith("ansible_host"):
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self.add_host_resource(resource)
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elif resource.type().startswith("ansible_group"):
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self.add_group_resource(resource)
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def to_dict(self):
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'''
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Generate the file Ansible inventory structure to be serialized into JSON
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for consumption by Ansible proper.
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'''
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out = {
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"_meta": {
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"hostvars": {}
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}
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}
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for hostname, host in self.hosts.items():
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host.build()
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for group in host.groups:
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self.update_groups(group, hosts=[host.hostname])
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out["_meta"]["hostvars"][hostname] = host.get_vars()
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for groupname, group in self.groups.items():
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group.build()
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out[groupname] = group.to_dict()
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return out
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class AnsibleHost(object):
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'''
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AnsibleHost represents a host for the Ansible inventory.
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'''
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def __init__(self, hostname, source=None):
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self.sources = []
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self.hostname = hostname
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self.groups = set(["all"])
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self.host_vars = {}
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if source:
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self.add_source(source)
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def update(self, groups=None, host_vars=None):
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'''Update host resource with additional groups and vars.'''
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if host_vars:
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self.host_vars.update(host_vars)
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if groups:
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self.groups.update(groups)
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def add_source(self, source):
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'''Add a Terraform resource to the sources list.'''
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self.sources.append(source)
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def build(self):
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'''Assemble host details from registered sources.'''
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self.sources.sort(key=lambda source: source.priority())
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for source in self.sources:
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if source.type() == "ansible_host":
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groups = source.read_list_attr("groups")
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host_vars = source.read_dict_attr("vars")
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self.update(groups=groups, host_vars=host_vars)
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elif source.type() == "ansible_host_var":
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host_vars = {source.read_attr(
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"key"): source.read_attr("value")}
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self.update(host_vars=host_vars)
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self.groups = sorted(self.groups)
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def get_vars(self):
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'''Get the host's variable dictionary.'''
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return dict(self.host_vars)
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class AnsibleGroup(object):
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'''
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AnsibleGroup represents a group for the Ansible inventory.
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'''
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def __init__(self, groupname, source=None):
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self.groupname = groupname
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self.sources = []
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self.hosts = set()
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self.children = set()
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self.group_vars = {}
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if source:
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self.add_source(source)
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def update(self, children=None, hosts=None, group_vars=None):
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'''
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Update host resource with additional children, hosts, or group variables.
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'''
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if hosts:
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self.hosts.update(hosts)
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if children:
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self.children.update(children)
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if group_vars:
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self.group_vars.update(group_vars)
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def add_source(self, source):
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'''Add a Terraform resource to the sources list.'''
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self.sources.append(source)
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def build(self):
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'''Assemble group details from registered sources.'''
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self.sources.sort(key=lambda source: source.priority())
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for source in self.sources:
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if source.type() == "ansible_group":
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children = source.read_list_attr("children")
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group_vars = source.read_dict_attr("vars")
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self.update(children=children, group_vars=group_vars)
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elif source.type() == "ansible_group_var":
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group_vars = {source.read_attr(
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"key"): source.read_attr("value")}
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self.update(group_vars=group_vars)
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self.hosts = sorted(self.hosts)
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self.children = sorted(self.children)
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def to_dict(self):
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'''Prepare structure for final Ansible inventory JSON.'''
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return {
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"children": list(self.children),
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"hosts": list(self.hosts),
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"vars": dict(self.group_vars)
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}
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def _execute_shell():
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tf_workspace = [TERRAFORM_PATH, 'workspace', 'select', TERRAFORM_WS_NAME]
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proc_ws = Popen(tf_workspace, cwd=TERRAFORM_DIR, stdout=PIPE,
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stderr=PIPE, universal_newlines=True)
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_, err_ws = proc_ws.communicate()
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if err_ws != '':
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sys.stderr.write(str(err_ws)+'\n')
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sys.exit(1)
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else:
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tf_command = [TERRAFORM_PATH, 'state', 'pull']
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proc_tf_cmd = Popen(tf_command, cwd=TERRAFORM_DIR,
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stdout=PIPE, stderr=PIPE, universal_newlines=True)
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out_cmd, err_cmd = proc_tf_cmd.communicate()
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if err_cmd != '':
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sys.stderr.write(str(err_cmd)+'\n')
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sys.exit(1)
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else:
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return json.loads(out_cmd)
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def _backup_tf(tfstate):
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# Crates a state backup in case we lose Consul
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with open(TERRAFORM_BPK, 'w') as f:
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f.write(json.dumps(tfstate.state_json))
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def _backup_ansible(inventory):
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# Crates a state backup in Ansible inventory format
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text = '# NOTE: This file is generated by terraform.py\n'
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text += '# For emergency use when Consul fails\n'
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text += '[all]\n'
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for hostname, host in sorted(inventory.hosts.items()):
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host_vars = {k: v for k, v in host.host_vars.items() if k != 'hostname'}
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vars_text = " ".join(f"{k}={v}" for k,v in host_vars.items())
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text += f"{hostname} {vars_text}\n"
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text += '\n'
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for name, hosts in sorted(inventory.groups.items()):
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if name in ['_meta', 'all']:
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continue
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text += '[{}]\n'.format(name)
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for hostname in sorted(hosts.hosts):
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text += '{}\n'.format(hostname)
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text += '\n'
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with open(ANSIBLE_BKP, 'w') as f:
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f.write(text)
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def _main():
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try:
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tfstate = TerraformState(_execute_shell())
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inventory = AnsibleInventory()
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for resource in tfstate.resources():
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if resource.is_ansible():
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inventory.add_resource(resource)
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sys.stdout.write(json.dumps(inventory.to_dict(), indent=2))
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# backup raw TF state
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_backup_tf(tfstate)
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# backup ansible inventory
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_backup_ansible(inventory)
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except Exception:
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traceback.print_exc(file=sys.stderr)
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sys.exit(1)
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if __name__ == '__main__':
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_main()
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